Weather Hazards and Climate Change

• Atmospheric Circulation


  The general movements of air around the Earth due to pressure and temperature
• Climate Change


  A distinct change in global or regional patterns of climate, such as changes in temperature or precipitation patterns
• Convection Current


  The movement of a fluid caused by a difference in temperature or density
• Coriolis Effect


  The effect of the earth's rotation on wind movements
• Cyclone


  A tropical cyclone that hits Oceania or Madagascar
• Drought


  A prolonged dry period in the natural climate cycle that can occur anywhere in the world (WHO Definition)
• Eccentricity


  A measure of how much the Earth's orbit around the Sun changes from a circular shape to an ellipse
• Eye


  An area of a tropical cyclone with extremely low pressure and calm conditions
• Eyewall


  An area of a tropical cyclone with the most intense, powerful winds and torrential rain
• Ferrel Cell


  At around 60° North and South of the equator, moist air rises, and travels to lower latitudes at around 30°. Here, it sinks along with air travelling from the equator
• Fossil Fuels


  Fuels made up of the remains of organic material, such as oil, coal and gas
• Greenhouse Gases


  Gases in the Earth's atmosphere that trap energy in the Earth's system and contribute to the greenhouse effect (carbon dioxide, methane, water vapour and nitrous oxides)
• Hadley Cell


  Warm, moist air rises near the equator and then cools as it travels to higher latitudes (30°) where it sinks
• Hazard Risk


  The probability that a natural hazard will negatively affect a population
• Hurricane


  A tropical cyclone that hits the USA, Latin America or the Caribbean
• Hydrological Drought


  When reduced precipitation impacts water supply. There is a decrease in streamflow, soil moisture, reservoir, lake and groundwater levels
• Ice Core


  A cylinder of ice extracted from an ice sheet or glacier, which is used to analyse past environmental conditions
• Immediate Responses


  Actions taken as soon as the hazard occurs and in its immediate aftermath (hours, days, and potentially a week or so after the event)
• Intertropical Convergence Zone (ITCZ)


  An area surrounding the equator where global winds converge, causing an area of low pressure with rainy conditions
• Long-term Responses


  Actions taken after the immediate responses when the effects of the hazard have been minimised (weeks, months, and years after the event)
• Meteorological Drought


  When the amount of precipitation received in an area is below average
• Milankovitch Cycles


  The cyclical variations in the Earth's orbit around the Sun. Includes: Eccentricity, Obliquity (tilt) and Precession (wobble of Earth's axis)
• Obliquity (or Axial Tilt)

  The tilt of the Earth's axis, which changes from 21.5° and 24.5°
• Ocean Currents


  The predictable, continuous circulation of ocean water which transfers heat around the globe
• Polar Cell


  At 60° north or south of the equator, moist air rises, and travels to the poles (90°), where it sinks
• Precession


  The 'wobble' of the Earth's axis
• Pressure Belt


  A region of the Earth which is generally under the same pressure
• Primary Effects


  The effects that are directly caused by the hazard itself
• Quaternary Period


  The geological time period which began 2.6 million years ago and extends into the present
• Secondary Effects


  Impacts that are a result of the primary effects of a hazard
• Storm Surge


  When a tropical cyclone pushes a large amount of sea water onto the shore, causing a rise in sea level
• Subduction


  A process that occurs at a destructive plate boundary when a plate is pushed below another plate, forcing it to sink into the asthenosphere
• The Enhanced Greenhouse Effect


  A process where the Earth's surface is heated by the greenhouse effect at an increased rate due to larger greenhouse gas emissions from human activities
• The Greenhouse Effect


  A natural process where greenhouse gases trap the energy from the Sun inside the Earth's atmosphere, warming the Earth's surface
• Track


  A typical pathway that a tropical cyclone takes which is driven by global wind circulation
• Tree Rings


  A ring in a tree trunk that grows annually, indicating the conditions in the year it grew
• Tropical cyclone

  A very large, spinning storm with high winds and torrential rain that forms in the tropics
• Typhoon


  A tropical cyclone that hits India, Japan or the Philippines